1. Field of the Invention
The present invention relates to steering mechanisms. More particularly, the present invention relates to steering mechanisms for use on non-riding, ground engaging equipment.
2. Related Art
Various types of non-riding, ground engaging equipment are used in agricultural, arboricultural, and horticultural applications. By "non-riding" is meant a piece of equipment on which the operator or user does not actually sit or ride. Rather, the operator of such equipment typically pushes or pulls it over the surface of the ground. Such equipment can be powered, for example by an engine, or non-powered. Examples of this type of equipment include mowers, edgers, and trenchers.
The need to dig a trench arises for many different reasons. Trenches are needed for the installation of underground sprinkler systems, and for burying of cable, pipe, or wire. These types of trenches typically have two vertical faces. A "bed defining" trench is often used between shrubbery beds and grass areas to define the extent of the shrubbery bed. The bed defining trench also serves as a dam to hold the mulch in the bed, and permits the top of the mulch to be at the level of the grass. The bed defining trench serves to provide a clear separation of the shrubbery beds from the remainder of the landscape. The shrubbery beds can then be covered with mulch, or treated with chemicals, to prevent grass from growing. Ideally, a bed defining trench has a straight vertical face adjacent the sod or grass area, and a sloping face that extends toward the shrubbery bed.
In some applications it is desired to dig a trench that runs in a line that is nearly perfectly straight. Such a straight trench is often needed when laying cable, pipe, or wire, but can also be required for bed defining trenches in a landscaping application. It is very often necessary in landscaping applications to be able to dig a bed defining trench that includes graceful and smooth arcs and curves, as well as circular tree rings.
Various non-riding trenchers have been developed for digging vertical trenches and for digging bed defining trenches. Such trenchers typically have a handle at one end of the device that allows the operator to either pull or push the device over the surface of the ground. In one type of device, the trencher has a pair of wheels at the end of the device remote from the operator, and a single caster-like wheel at the handle end of the device adjacent the operator. In one such device, the single wheel swivels independently of the handle. As such, none of the wheels of the trencher can be steered by the operator. Consequently, the trenches dug by the trencher are not straight. Additionally, to produce arcs or curves, the trencher must be dragged over the surface of the ground. When the single swivel wheel hits a rock or other obstacle, it is very difficult to keep the trencher on a curved course. As such, it cannot easily be used to produce smooth, graceful curves and arcs.
In another type of trencher that has a single wheel at the handle end, the handle is formed by the forks of the single caster wheel. However, the control provided by this single wheel is insufficient to produce smooth, graceful curves. Additionally, devices that have a single wheel at the handle end are not as stable as devices that have a pair of wheels at each end. This stability problem is particularly acute when the device is being used to produce arcs and curves, and when the device is being used on a hill or slope.
Other trenchers include a pair of wheels at each end. Such devices are described, for example, in U.S. Pat. Nos. 5,226,248 and 5,355,597, the entirety of both of which is incorporated herein by reference. The device described in the foregoing patents is particularly suited for digging bed defining trenches. However, this device is not steerable. Therefore, to make arcs and curves with the device, it is necessary to slide the wheels to drag the device from side-to-side in order to cut a curved trench.
The problem of steering a trencher through arcs and curves is given as an example of the need for a steering mechanism for non-riding ground engaging equipment. As will be described in detail below, the present invention overcomes the deficiencies of and problems associated with the conventional technology noted above.